The present invention relates to a window with an aerial for motor vehicles, comprising an electrically conductive coating used as an aerial conductor and a connection element which is coupled capacitively to the electrically conductive coating by means of a coupling electrode with interposition of an insulating layer.
Windows with an aerial comprising transparent coatings which can conduct electricity are known in various embodiments. The coatings are generally coatings that reflect infrared radiation, which above all have a sun protection function. These coatings which reflect infrared radiation mostly have one or more functional layers of silver and have a surface resistance of about 4 .OMEGA./.quadrature. for an optical transmission of 75%. By virtue of their electrical conduction property, these layers can be used as a reception aerial for radio reception.
The conductive layers, which essentially consist of multiple layers applied by sputtering, generally lie inside a laminated glass window. They may be arranged directly on the surface of one of the two panes or on the surface of a thin transparent support sheet which is connected to the two panes by means of two thermoplastic adhesive sheets.
Document DE 19 735 395 A1 describes how to capacitively couple a conductive layer used as an aerial to the connection conductor via which the aerial signal is transmitted to the radio receiver. The capacitive coupling is then carried out in such a way that an electrode produced in the form of a strip is pressed onto that face of the laminated glass window which faces the passenger compartment, whereas the conductive layer is arranged inside the laminated glass window. The length of the electrode in the form of a strip must be more than 5 cm and its width must lie between 5 and 10 mm. The coupling electrode must be installed at as large as possible a distance from the conducting window frame, that is to say inside the visible surface of the window. If it is desired to avoid the effect which is detrimental in optical terms which results therefrom, the decorative frame of opaque enamel generally applied to the edge of the window must be produced in a corresponding width. The area of the window is thus further reduced, and the widened decorative frame also involves a reduction in the apparent image of the window of the vehicle.